Q: My water PPM is 300. I want nutrient PPM of 500. In such a case after adding the nutrient should I be aiming for a PPM of 800?
A: Yes, definetely

Q:Should I use underground water (borewell) that has been softened by a water softening unit (ion exchange method of water softening) or Reverse Osmosis (RO) water? The underground water PPM is 300 PPM while the RO is
A: I would bypass the water softener. It introduces sodium, which is not such a good idea for plants.
One thing you could consider is to cut down on your calcium content, since that comes free with your borewell water. Bonus !

Hi Srikanth
Actually not a newbie question, rather a though-one...

>>1) My water PPM is 300. I want nutrient PPM of 500. In such a case after adding the nutrient should I be aiming for a PPM of 800?In case your water would have 100, 150 or even a little more, I'd recommend to aim for a total of (X=water ppm) X plus your 500 ppm, regardless what the composition of your water was, except high chlorine or sodium.

But 300 ppm is a LOT and that's a different matter. You could even say that water with 300 ppm is actually not suited for hydroponics. Unless,.... you have a analyses of the water. If there is not too much chlorine or/and sodium you could adopt through the choice of the product or with a specific formula. If you'd simply take the 3 parts of "unknown" and add 5 parts of a known and actually (supposed to be) balanced composition, you'd in fact end up with some kind of 3/5 unknown vs. known formula - wouldn't you? That's not good or close enough, at least for my understanding of a balanced and adequate formula.

>>2) Should I use underground water (borewell) that has been softened by a water softening unit (ion exchange method of water softening) or Reverse Osmosis (RO) water? The underground water PPM is 300 PPM while the RO is Bore water: Same as for 1) unless you have an analyses of the 300 ppm, such water has to be classified as unsuitable.

>>The underground water after softening would have the calcium carbonate converted to sodium carbonate and calcium chloride. I am not sure what happens to the magnesium in the water (probably magnesium chloride).Sorry, no real good news here either, because not only the sodium isn't what we're aiming for, the chlorine isn't much of a bargain either.

Proposal: mix 50/50 of rainwater/"your water" or rainwater with /50 bore water (without reverse osmosis) , depending on best analyses of either, and aim for a total of 650-700 ppm.

The underground water after softening would have the calcium carbonate converted to sodium carbonate and calcium chloride. I am not sure what happens to the magnesium in the water (probably magnesium chloride)
The softener converts the calcium into sodium by exchanging the kations bonded in the resin. There's no chloride being released by the resin. Softened water is unsuitable because of the sodium content. It's OK for the laundry (only). But as Lucas suggested, you could incorporate the (estimated) calcium content in the nutrient formula.

Have I been missing something earlier, - or is there something unclear with your explanations Srikanth?

Anyway I have to correct something important here:

The water from the Reverse Osmosis with some 30 PPM is just fine. The lower the ppm of any water, the better it is for hydroponics. Use it and put your 500 on top of it (total 530 ppm).

But there is something unclear about the "softening process". Because water with 30 ppm from RO doesn't actually need to be softened. Is there some device called "softener", or is it perhaps re-mineralized instead, because it got too poor in minerals by RO (for using it as drinking water)?

However, both calcium chloride and magnesium chloride (as mentioned by Srikanth) obviously contain chloride. If the data I have are correct, 1 gr of calcium chloride dissolved in one gallon of water equals about 127 ppm of chloride (vs. only 72 ppm of calcium).

Hmmm, I get:
1gr of CaCl2(M=111)dissolved in one litre of water gives me: 361ppm Ca and 639ppm Cl. But dissolved in one gallon this would make (div by 3.785) 95ppm Ca and 169ppm Cl.

Did I go wrong somewhere ?

Now, if you were to assume that the 300ppm is made-up by CaCl2, then you would get: 108ppm Ca and 192ppm Cl.
But the best thing is to ask for an analysis of the borewell water. (It DOES look like a perfect source of Ca to me.)

I am not assuming anything from that "famous 300 ppm" anymore, until I've seen a complete analyses ;-)

Did you go wrong somewhere?
Perhaps, - all depends on what you were referring to.

As calcium chloride (at least as it is commonly used) is a chemical compound that has either been produced from limestone or is a byproduct from other chemical manufacturing - it has to be seen and treated as a chemical product. Products come in different grades and purity (purity of CaCl is ranging from approximatively 70-96%). That is why its ACTUAL content in (ppm of) elements can't be calculated by its molecular weight only.

The calcium chloride I was referring to is commonly used food grade-, but has only a elemental purity of 75%. Hence, simply take 75% of the molecular weight of the component, and you've got the ACTUAL 127 ppm of chloride and the 72 ppm of calcium contained in that particular (one has to add) calcium chloride. Actually it is the data from the CaCl I always use when composing and calculating my nutrient formulas.

Does calcium chloride look like a good source of calcium to me too?

Firstly: chlorine for instance is an essential micro nutrient in plant nutrition and is supposed to aid root growth. Still, the average in soils (top part) is only about 10 ppm.

Example: I'm only using calcium chloride as small part of my formulas, and only as long as I can limit the TOTAL chlorine content in a nutrient solution to a maximum of 60-70 ppm. I'm using just enough CaCl to provide around 40 ppm of Ca , which obviously brings these some 70 ppm of chlorine to the formula. That's enough to complement the Ca provided bay another component called calcium nitrate. Indeed CaCl (when sparingly used) is actually a particular useful additive when composing formulas that require relatively low nitrogen- in relation to normal or high calcium content. Otherwise, with such formula it's not possible to supply enough calcium through calcium nitrate only, without exceeding your N-target.

But in case some tap water already has high chlorine content, - this component is obviously NOT suited as such an additive and no good source of Ca, not even to complement some calcium in a particular case.

Best is always to have pure water with lowest mineral or saline (=low ppm) content possible, - and there you go with any formula and any suited ingredients you want.

Hello All,

Thanks a lot for answering my questions. I was expecting an email notification for the responses which I did not receive (Not in the spam folder either), hence I could not respond sooner.

I think I have not stated my question in full.

Location: Hyderabad, India
Purpose: Home Garden
Original Source of Water: Borewell
Softener: The borewell water is treated by the softener. This softened water is sent to an overhead storage system for general household use.
RO: The softened water is fed to the input of the RO system. This is mainly for drinking purposes.

The 300 and 30 PPM readings of the softened borewell water and the RO water is from a TDS meter. I can bring down the PPM of the RO water to 10 PPM if I have it cleaned and serviced.

The RO system is not an RO plant. It is a small unit for drinking purposes (Capacity 25L/hr).

Generally the PPM of the borewater goes up during summer.

Note: I will be trying out Hydroponics on my roof purely as a hobby.

After reading through the responses it seems like the borewater is probably ruled out until I have a chemical analysis done. Until then, I should stick to RO.

Is this understanding correct?

Thanks,
Srikanth

@ Srikanth: Yes, that would be fine

@ Lucas: The calcium chloride I was referring to is commonly used food grade-, but has only a elemental purity of 75%. OK, that explains it.

Srikanth, yep - stick with the RO water. And the lower the ppm, the better for your formula - especially in your case.

And let me just add one thing: a lot has been said (at least from my part) why and what preferably not doing, - but not much yet about why the targeted ppm of the basic formula (500 in this case) should be added on top. Well it's simple; because the whole 500 ppm actually contain what is needed in your nutritional plan. If you wouldn't add it completely, it would simply not be the concentration that is was supposed to be. And because your formula is rather low in concentration, - it is even one reason more to do so.

Good luck!
Lucas

Thank you all.